1. Technical Field
The invention relates to a semi-circular plain bearing shell with two circumferential end portions, a radial inner side, along which a sliding surface is arranged, and having on the inside in this area on at least one of the end portions, formed, separate grooves that run in the circumferential direction and extend in the axial direction.
2. Related Art
Typical applications for the generic slide bearing shell are the connecting rod or crankshaft main bearings in internal combustion engines. Slide bearing shells of the generic type, for example, are known from German patent application DE 10 2005 037 502 or DE 101 63 292 Al.
Both writings deal with two mutually conflicting problems:
A bearing is formed from two such sliding bearing shells, whose partial surfaces —which are the front-facing end surfaces in the circumferential direction —lie on top of one another. Minor inaccuracies of the assembled bearing result in the partial surfaces being not precisely coordinated, with the result that the inner edge of the partial surface of a bearing shell projects radially inward relative to the inner edge of the adjacent partial surface of the other bearing cup. This hydrodynamic lubrication can be hampered due to this offset, which can lead to additional wear and tear on the bearing. To prevent this, the bearing shells are known to have a so-called exposure on the inner side of its peripheral end portions, where the side 30 of the sliding layer reduces the thickness of the slide bearing shell over the entire axial length. On the one hand, however, these open exposures basically have the disadvantage of collapsing the hydrodynamic oil pressure at this point and, worse still, the lubricating oil can also leak out of the bearing shell in the axial direction at this point, which increases the required oil capacity.
To counter this problem, oil grooves —which are arranged in parallel and immediately adjacent to each other —are provided according to DE 101 63 292 Al in this area where the exposure is usually introduced. These grooves are produced by forming a spiral groove with a groove- spacing corresponding to the drilling tool feed, and with circumferential ridges remaining between the grooves. These ridges are removed due to wear when the bearing shell is being broken in, so that the initial wear forms the exposure itself, and in fact, does this exactly to the extent-that is required in the operating state.
Oil grooves are provided in the other sliding surface areas of the bearing shell, but they have a smaller depth, and thus provide more obtuse ridges that are more resistant to wear. The differently configured oil grooves are formed by drilling the bearing shell, but require different tools and various drilling processes, which increases manufacturing costs.
In patent application DE 10 2005 037 502, it is proposed to arrange the oil grooves in the exposed clear areas that are tilted and oriented in the flow direction of the lubricating oil at the centre line of the bearing shell. The grooves that are oriented in the direction of the lubricating oil's flow, which is predetermined by the direction of rotation of the shaft, run towards the midline, the oil from the edge region of the exposure guided inwards and counteracted in this way an axial oil outflow in the exposure areas.